U.S. patent number 7,928,741 [Application Number 12/426,956] was granted by the patent office on 2011-04-19 for oil monitoring system.
This patent grant is currently assigned to Voelker Senors, Inc.. Invention is credited to Joe D. Hedges, Paul J. Voelker.
United States Patent |
7,928,741 |
Hedges , et al. |
April 19, 2011 |
Oil monitoring system
Abstract
An embodiment of the present invention provides for a sensing
element comprising a non-conductive housing with three chambers for
detecting oil conductivity, additive depletion and oxidation, and
water contamination, respectively. Through the monitoring of an
array of oil sensors, an early warning of oil degradation due to
oxidation is provided. The monitoring system further detects excess
soot, water and other contaminants in the oil. The oil sensor array
and related monitoring system decrease the likelihood of
catastrophic engine failure through the early detection and warning
of a decrease in oil quality thereby reducing vehicle owner outlays
for servicing and disposal fees while further aiding in the
satisfaction of environmental protection regulations.
Inventors: |
Hedges; Joe D. (Portola Valley,
CA), Voelker; Paul J. (Fremont, CA) |
Assignee: |
Voelker Senors, Inc. (Palo
Alto, CA)
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Family
ID: |
38437986 |
Appl.
No.: |
12/426,956 |
Filed: |
April 20, 2009 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20090201036 A1 |
Aug 13, 2009 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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11676738 |
Feb 20, 2007 |
7521945 |
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60774749 |
Feb 17, 2006 |
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60782959 |
Mar 15, 2006 |
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Current U.S.
Class: |
324/698;
73/53.05 |
Current CPC
Class: |
G01N
33/2888 (20130101) |
Current International
Class: |
G01R
27/26 (20060101); G01N 33/26 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0442314 |
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Aug 1991 |
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EP |
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0584557 |
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Jul 1992 |
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EP |
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939049 |
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Oct 1963 |
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GB |
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Other References
Tim Sullivan, "Oil Sludge Bedevils VW," Lube Report, Aug. 31, 2004,
http://www.lubereport.com/e.sub.--article000298526.cfm?x=b3t4ghV,bhb871W.
cited by other .
"Oil Advantage: In-line Oil Monitoring System," Voelker Sensors
Inc., 2004. cited by other .
"Assured Oil Performance at a Glance," Voelker Sensors Inc., 2004.
cited by other .
"Oil Advantage: Low Cost In-line Oil Monitoring System," Voelker
Sensors Inc., 2006, VSI. cited by other .
Elecia White, "Due for an Oil Change?" Putting Sensors to Work,
Sensors, Apr. 2005, pp. 27-29. cited by other .
Mike Allen, "Dirty Deeds Done Dirt Cheap," Car Clinic, Car Care,
Popular Mechanics, Aug. 1993, p. 71. cited by other .
R.T. Mookken et al., "Dependence of Oxidation Stability of Steam
Turbine Oil on Base Oil Compositio .COPYRGT.," Journal of the
Society of Tribologists and Lubrication Engineers, Dec. 3, 1996,
pp. 19-24. cited by other .
W.F. Bowman et al., "Application of Sealed Capsule Differential
Scanning Calorimetry-Part II: Assessing the Performance of
Antioxidants and Base Oils .COPYRGT." Technical Paper, Lubrication
Engineering, May 1999, pp. 22-29. cited by other .
W.F. Bowman et al., "Application of Sealed Capsule Differential
Scanning Calorimetry-Part I: Predicting the Remaining Useful Life
of Industry-Used Turbine Oils .COPYRGT.," Journal of the Society of
Tribologists and Lubrication Engineers, Aug. 18, 1998, pp. 19-24.
cited by other .
Jun Dong et al., "Rapid Determination of the Carboxylic Acid
Contribution to the Total Acid Number of Lubricants by Fourier
Transform Infrared Spectroscopy .COPYRGT.," Technical Paper,
Journal of the Society of Tribologists and Lubrication Engineers,
Aug. 30, 1999, pp. 12-20. cited by other .
Han-Sheng Lee et al., "In-Situ Oil Condition Monitoring in
Passenger Cars .COPYRGT.," Journal in Society of Tribologists and
Lubrication Engineers, 1993, vol. 50, No. 8, pp. 605-611. cited by
other .
R.E. Kauffman, "Rapid, Portable Voltammetry Techniques for
Performing Antioxidant, Total Acid Number (TAN) and Total Base
Number (TBN) Measurements .COPYRGT.," Technical Papers, Journal of
the Society Tribologists and Lubrication Engineers, Jan. 1998, pp.
39-46. cited by other .
Atsushi Sato et al., "Electrical Conductivity Method for Evaluation
of Oxidative Degradation of Oil Lubricants .COPYRGT.," Journal of
the Society of Tribologists and Lubrication Engineers, Jul. 1992,
vol. 48, No. 7, pp. 539-544. cited by other.
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Primary Examiner: Natalini; Jeff
Attorney, Agent or Firm: Carr & Ferrell LLP
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application is a continuation and claims the priority
benefit of U.S. patent application Ser. No. 11/676,738, now U.S.
Pat. No. 7,521,945, filed Feb. 20, 2007, which claims the priority
benefit of U.S. provisional patent application No. 60/774,749 filed
Feb. 17, 2006 and U.S. provisional patent application No.
60/782,959 filed Mar. 15, 2006. The disclosure of the
aforementioned applications is incorporated herein by
reference.
The present application is related to U.S. Pat. No. 5,435,170,
entitled "Method and Apparatus for Fluid Quality Sensing"; U.S.
Pat. No. 5,777,210, entitled "Oil Quality Sensor Measuring Bead
Volume"; and U.S. Pat. No. 5,789,665 entitled "Oil Quality Sensor
for Use in a Motor Oil." The disclosure of these commonly owned
patents is incorporated herein by reference.
Claims
What is claimed is:
1. An oil quality monitoring system, comprising: a sensing element
that generates oil measurement data associated with oil quality of
a monitored oil sample, the sensing element comprising: a housing,
and a plurality of chambers within the housing, the plurality of
chambers including a first chamber and a second chamber, the first
chamber including a first bead that responds to a first property of
the monitored oil sample, the second chamber including a second
bead that responds to a second property of the monitored oil
sample; and a monitoring device coupled to the sensing element, the
monitoring device comprising an application specific integrated
circuit that differentially analyzes the oil measurement data from
the plurality of chambers, and wherein the oil monitoring device
displays an indicia of oil quality of the monitored oil sample in a
user interface based on the differential analysis of the oil
measurement data, the differential analysis including comparing a
difference between oil measurement data from the first and second
chambers.
2. The oil quality monitoring system of claim 1, wherein the first
bead includes an ionically charged group.
3. The oil quality monitoring system of claim 1, wherein the first
bead responds to a concentration of water, a concentration of soot,
a pH, or a concentration of an additive package in the monitored
oil sample.
4. The oil quality monitoring system of claim 1, wherein the
plurality of chambers includes a third chamber containing a third
bead, and the differential analysis includes comparing a difference
between oil measurement data from two of the first, second, or
third chambers.
5. The oil quality monitoring system of claim 1, wherein the first
property is associated with any of a concentration of water, a
concentration of soot, a pH, or a concentration of an additive
package in the monitored oil sample, and the second property is
associated with any other of the concentration of water,
concentration of soot, pH, or concentration of the additive package
in the monitored oil sample.
6. The oil quality monitoring system of claim 1, wherein the first
chamber includes only the first bead, and the second chamber
includes a plurality of beads.
7. The oil quality monitoring system of claim 1, wherein the oil
measurement data include conductivities within at least two
chambers of the plurality of chambers.
8. The oil quality monitoring system of claim 1, further comprising
a thermistor coupled to the monitoring device, the thermistor
disposed to measure oil temperature.
9. The oil quality monitoring system of claim 1, wherein at least
one chamber from the plurality of chambers is covered by a filter
that prevents suspended particles from passing into the covered
chamber.
10. An oil quality monitoring system, comprising: an array of
sensing elements that generate oil measurement data associated with
oil quality of a monitored oil sample, each of the sensing elements
in the array of sensing elements comprising: a housing, and a
plurality of chambers within the housing; and a monitoring device
coupled to the array of sensing elements, the monitoring device
comprising a software module stored in memory and executable by a
processor to differentially analyze the oil measurement data
generated by the array of sensing elements and wherein the oil
monitoring device displays an indicia of oil quality of the
monitored oil sample in a user interface based on the differential
analysis of the oil measurement data.
11. The oil quality monitoring system of claim 10, wherein the oil
measurement data is batched and collectively analyzed by the
monitoring device.
12. The oil quality monitoring system of claim 10, wherein the oil
measurement data is serially analyzed by the monitoring device.
13. The oil quality monitoring system of claim 10, wherein portions
of the oil measurement data are analyzed in parallel by the
monitoring device.
14. The oil quality monitoring system of claim 10, wherein the oil
measurement data are from at least two chambers of the plurality of
chambers in each of at least two sensing elements in the array of
sensing elements.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to measurement and testing
for liquid analysis. More specifically, the present invention
relates to the analysis of natural and synthetic oils for the
purpose of detecting oil degradation and, further, for detecting
the presence of contaminates such as soot, fuel and water.
Oxidation and the presence of contaminates may be interpreted as an
indication of the quality of the oil or any other non-polar
liquid.
2. Description of the Related Art
Determining oil quality is a complex issue. Four methods of
measuring and testing lubricating oil quality are generally
accepted in the art: infrared spectroscopy, pH measurement,
viscosity, and prediction of degradation.
Infrared spectroscopy utilizes a portion of the infrared region of
the electromagnetic spectrum for analyzing organic compounds. For
example, photon energies associated with the wavelength range of
2,500 to 16,000 nm, which corresponds to a frequency of
approximately 1.9.times.10.sup.13 to 1.2.times.10.sup.14 Hz, are
not large enough to excite electrons. These photon energies may,
however, induce vibrational excitation of covalently bonded atoms
and groups. As molecules experience a variety of vibrational
motions characteristic of their component atoms, virtually all
organic compounds will absorb infrared radiation that corresponds
(in energy) to these vibrations. Infrared spectrometers obtain
absorption spectra of compounds that are a unique reflection of
their molecular structure.
While infrared spectroscopy offers the advantage of determining a
number of oil qualities--including and in addition to
lubricity--this methodology requires the removal of an oil sample
from a source (e.g., removing oil from the motor of an automobile)
and placing the oil sample in an infrared spectrometer. In addition
to being expensive, this methodology is not conducive to
`on-the-fly` testing. Absent infrared spectrometers being
introduced as standard equipment in automobiles and other machines
that utilize natural and synthetic oils, infrared spectroscopy
cannot be utilized to provide instantaneous indications of oil
quality and/or that oil needs to be changed.
The second method of measuring and testing lubricating oil
quality--pH measurement--is a logarithmic measurement of the number
of moles of hydrogen ions per liter of solution. Thus, pH measures
the hydrogen ion concentration in a liquid solution such as natural
and synthetic oils. Low pH values (e.g., 0) indicate acidity and
high pH values (e.g., 14) indicate causticity. Continual process
monitoring and control of pH requires the use a specially prepared
electrode (i.e., the measurement electrode). This specially
prepared measurement electrode is designed to allow hydrogen ions
in the solution to migrate through a selective barrier thereby
producing a measurable potential difference proportional to the
solution's pH.
While the pH of oil provides an indication of changes in acidity or
causticity with regard to the presence (or absence) of certain
acids, pH does not measure oil lubricating quality. Further, pH
measurements do not determine if the oil has degraded due to
foreign particles and contaminants such as water or metal
particulate. Additionally, pH measurements can be skewed by the
presence of volatile acids that evaporate over time at certain
operating temperatures. The presence and/or subsequent evaporation
of those acids can provide a false and/or inconsistent pH reading
that is not relative to the actual quality of the oil being
measured. A pH sensor apparatus, too, is expensive and not
particularly suited for the environment of the oil pan of an
internal combustion engine.
The third measurement methodology--prediction of degradation--is
simple to a fault. Based on the knowledge that oil maintains a
particular quality over a period of time, the mileage traversed
since a previous oil change in a vehicle can be utilized to inform
the owner of the vehicle that it is time to replace the oil. The
timing of the indicia of replacement (e.g., the activation of a
dashboard warning light) is based on the prediction of degradation
and that the oil is no longer providing particular performance
guarantees as governed by the quality of the oil.
This methodology, however, does not take into account the various
qualities or quantities of oil that may be used in a particular
vehicle. This methodology further fails to account for the
particularities of the engine operating environment (e.g., engine
wear independent of the oil quality) in addition actual driving
conditions (e.g., city or highway, summer or winter, and so forth).
This methodology, in addition to its overall inaccuracy, provides
no qualitative or quantitative information regarding oil condition
in that the indicia of the need for oil replacement is purely
binary (i.e., time-to-change or not time-to-change).
A fourth technique measures the viscosity of the oil. As a result
of the oxidation process, oil becomes thicker. A thickening of the
oil can be an indication of the extent of oil breakdown.
While viscosity can provide an indication of oil wear, viscosity is
dependent on the temperature and the particular viscosity
improvement package added to the oil. For a viscosity measurement
to provide an accurate measurement of oil quality, the temperature
and type of viscosity improvement package must be known. The
presence of contaminates will further increase or decrease the
viscosity of a particular oil sample thereby hampering
measurement.
As previously noted, base engine oils are non-polar and provide
near-zero conductivity when clean. As the oil wears, the oil slowly
begins to oxidize and exponentially increase in polarity as is
shown in FIG. 1. FIG. 1 illustrates oil that, initially, is clean
and non-polar. In the presence of O.sub.2 and heat, the oil begins
to degrade. This application of O.sub.2 and heat would occur
through, for example, the normal and ongoing use of the oil in an
automobile.
This partially degraded oil, as also shown in FIG. 1, begins to
take on polar characteristics. Through the continued application of
O.sub.2 and heat, the oil becomes even more degraded and takes on
even grater polar characteristics as further shown in FIG. 1.
Increased polarity causes the oil to change is dielectric constant,
which in turn leads to increased capacitance.
Most fully formulated oils incorporate deposit control additives,
anti-wear and extreme pressure additives, corrosion inhibitors, and
antioxidants. These protective additives generally consist of a
polar salt head and a nonpolar hydrocarbon tail to trap harmful
byproducts of oil wear. Depending on the exact concentration of
various additives, the oil's dielectric constant and conductivity
will vary according to the manufacturer, batch, and base type.
Clean and fully formulated oil typically has a higher starting
capacitance than that of worn base oil. Because of this higher
capacitance, electrical measurement of clean oil actually measures
the additive package and not the properties of the base oil. Oil
deterioration also results in a decrease of additives. As the
dielectric constant of the oil becomes greater than that of the
additives in the oil, useful direct oil analysis becomes difficult
if not impossible.
While a variety of means are known in the art to measure oil
pressure, there is a general lack of means to accurately and
effectively measure oil quality. Those sensors that do exist often
encounter the aforementioned problem of differentiating increases
in oil dielectric constant versus presence and quality of oil
additives. Measurement of oil quality is important in that the oil
in a vehicle or other mechanical device needs to be changed when
the oil loses its lubricity or becomes populated with
contaminates.
There is a general need in the art for means to measure oil quality
notwithstanding changes in oil dielectric constants. There is a
further need in the art for monitoring an array of sensors in the
oil thereby providing an early warning of degradation due to
oxidation and detecting excess soot and water.
SUMMARY OF THE INVENTION
The present invention provides for differential measurement of
specific conditions of contaminates in oil. Measurement of these
conditions may provide indicia of oil quality. While the breakdown
of the base stock alone is, in some instances, a key indicator of
oil wear, contamination by soot, fuel, and/or water may also be
important parameters with respect to determining oil quality. The
presently disclosed differential measurement technique employs
sensing elements that may measure substantially identical
properties with a single exception thereby allowing for a specific
attribute to be measured. Embodiments of the present invention may
be implemented in the context of the polystyrene bead matrices
disclosed in U.S. Pat. Nos. 5,435,170; 5,777,210; and 5,789,665.
The disclosure of the aforementioned patents has been previously
incorporated herein by reference.
In one embodiment, an oil quality monitoring system is comprised of
a sensing element configured to generate oil measurement data
associated with oil quality of a monitored oil sample, the sensing
element comprising a housing and a plurality of chambers within the
housing. A monitoring device is coupled to the sensing element. The
monitoring device includes an application specific integrated
circuit configured to differentially analyze the oil measurement
data generated by the sensing element. The device may be further
configured to display an indicia of oil quality of the monitored
oil sample in a user interface based on the differential analysis
of the oil measurement data.
In a further embodiment, an oil quality monitoring system is
provided that includes an array of sensing elements configured to
generate oil measurement data associated with oil quality of a
monitored oil sample. Each of the sensing elements in the array of
sensing elements includes a housing and a plurality of chambers
within the housing. A monitoring device coupled to the array of
sensing elements may provide for differential analysis of the oil
measurement data generated by the array of sensing elements. The
monitoring device may further display an indicia of oil quality of
the monitored oil sample in a user interface based on the
differential analysis of the oil measurement data.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates the wear of oil due to oxidation and heat
whereby the oil becomes more polar as is known in the prior
art.
FIG. 2 illustrates an exemplary real-time oil monitoring system as
may be implemented in accordance with an embodiment of the present
invention.
FIG. 3 illustrates an exemplary embodiment of a sensing element as
may be used in the present invention in addition to an inset
reflecting the installation of the sensing element in an oil
pan.
FIG. 4 is an exemplary illustration of the oil degradation
cycle.
FIG. 5A is an exemplary illustration of polymeric bead interaction
in a non-polar oil solution representative of relatively low
conductivity in an exemplary embodiment of the present
invention.
FIG. 5B is an exemplary illustration of polymeric bead interaction
in a polar oil solution representative of relatively high
conductivity in an exemplary embodiment of the present
invention.
FIG. 6A illustrates a single hydrophilic, polystyrene bead in an
environment without `free` water and reflecting relatively low
conductivity.
FIG. 6B illustrates a single hydrophilic, polystyrene bead in an
environment with `free` water and reflecting relatively high
conductivity.
FIG. 7 illustrates an exemplary interface as may be used with a
monitoring device of an exemplary embodiment of the presently
disclosed oil monitoring system.
DETAILED DESCRIPTION
FIG. 2 illustrates an exemplary real-time oil monitoring system 200
as may be implemented in accordance with an embodiment of the
present invention. An embodiment of the oil monitoring system 200
may comprise a monitoring device 210 for receiving and analyzing
data generated by a sensing element 220, which is in contact with
the oil or other fluid under observation.
Data generated by the sensing element 220 may be communicated to
the monitoring device 210 via a sensor signal cable 230. Sensor
signal cable 230, in one embodiment of the present invention, is an
RS-232 compliant serial cable wherein one end of the cable is
configured to exchange data with the monitoring device 210 and the
opposite end of the cable is configured to interface with sensing
element 220 as is discussed in greater detail in FIG. 3. Other data
cables are within the scope of the present invention subject to
proper configuration to allow for interface with the sensing
element 220 and monitoring device 210.
Monitoring device 210 may be further communicatively coupled to an
external computing device 250 such as a laptop computer, a PDA or
other mobile computing device that may be specially configured for
use with the oil sensing element 220 and monitoring device 210.
While mobility of the external computing device 250 may be
preferred in some environment (e.g., a garage), it is within the
scope of the present invention for the external computing device
250 to be a less-portable computing device such as a dedicated
workstation or desktop computer. Data may be exchanged between the
monitoring device 210 and external computing device 250 through,
for example, an external data cable 240 or a wireless network
connection.
External data cable 240 may comply with any number of data
transmission standards including Universal Serial Bus (USB) and
IEEE 1394 in addition to being a parallel or serial data cable. In
some embodiments of the present invention, monitoring device 210
may be configured for the introduction of, for example, a PCMCIA
wireless card or other wireless network adapter. In such an
embodiment, the monitoring device 210 may communicate data gathered
from the sensing element 220 as well as data analyzed by the
monitoring device 210 wirelessly using, for example, the 802.11x
wireless data standard to external computing device 250 such that
external data cable 240 is no longer necessary.
A wireless configuration of this nature would allow increased
mobility of the monitoring device 210 while still allowing, for
example, for the storage of oil data in a centralized repository
such as the aforementioned external computing device 250. Storage
of oil measurement data and analyses of that data may be useful in
determining if a particular vehicle or combustion engine might be
suffering from engine damage or some other defect in that the
particular vehicle or engine prematurely degrades oil. Such
information may be reflected by a series of oil analyses conducted
over time. These analyses may be stored, further analyzed, and
graphically illustrated in a report or some other organized
information presentation generated by external computing device
250. It should be noted that the presence of an external computing
device 250 is not required for the operation of the monitoring
device 210 in conjunction with sensing element 220.
The monitoring device 210, in one embodiment of the present
invention, receives and displays data indicative of the status of
the oil or another fluid under observation and analysis. The
interface of monitoring device 210 is discussed in more detail in
FIG. 7 below.
Monitoring device 210 and certain devices coupled to device 210 may
be powered by a variety of electrical power sources. In one
embodiment of the present invention, monitoring device 210 may be
electrically coupled to an AC transformer 260. In another
embodiment of the present invention, monitoring device 210 may be
electrically coupled to a DC transformer such as a cigarette
lighter adaptor whereby the system 200 may be used `on-the-road`
through use of an automobile's cigarette lighter power outlet.
Monitoring device 210 may further be powered by a replaceable or
rechargeable battery pack (not shown).
In an embodiment of the present invention, the monitoring device
210 may also comprise a thermistor configured to be used by a
microprocessor in the device 210 to compensate sensor readings for
thermal variations. For example, in one embodiment of the present
invention, the system 200 may only operate at engine operating
temperatures in excess of, for example, 70.degree. C. as the
conductivity of certain oils may be completely masked by the
additives below that temperature. Additionally, because oil is
formulated to work at automotive operating temperatures, the oil
may not properly lubricate at lower temperatures thereby distorting
data gathered by the sensing element 220.
FIG. 3 illustrates an exemplary embodiment of a sensing element 300
as may be used in the present invention. The inset of FIG. 3
reflects the sensing element 300 having been installed in an oil
pan. Sensing element 300 comprises an electrically nonconductive
housing 310 with three chambers (320, 330, and 340). Examples of
non-conductive materials for constructing the housing 310 include
but are not limited to ceramic, glass, plastic, woven fiberglass,
and paper impregnated with phenolic resin (e.g., Pertinax).
In some embodiments of the present invention, the housing 310 may
be constructed of an electrically non-conductive material. In other
embodiments, the housing 310 may instead be constructed of one or
more materials (which may or may not be electrically
non-conductive) and subsequently coated with an electrically
non-conductive material such as a non-conductive resin cured with
ultraviolet light and/or heat. In addition to non-conductive
resins, other suitable coating materials include but are not
limited to tape, paints and hot melt adhesives.
Housing 310 may be mounted in a conventional drain plug 350 such
that the sensing element 300 may be installed in a conventional oil
pan of an internal combustion engine. Mounting of the housing 310
may occur utilizing various industrial glues, sealants, adhesives
or other means so long as such mounting means do not interfere with
the sensing element 300's ability to communicate with cable
connector pins 360 as discussed in greater detail below.
By mounting the housing 310 of the sensing element 300 in a
conventional drain plug 350, an embodiment of the present invention
may be installed in older automobiles or equipment utilizing a
combustion engines without the need for extensive retrofitting as
the drain plug 350 may simply be threaded into the oil pan's drain
hole as would occur when changing the oil of a car. An embodiment
of drain plug 350 used for mounting the housing 310 of the sensing
element 300 may utilize 1/2''.times.20 threading such than an
exemplary sensing element 300 measuring approximately 2.8'' in
length occupies an internal depth of approximately 1.8''.
The particular mechanical interface (e.g., shape and threading
specifications) of the aforementioned drain plug 350 are exemplary
as are the particular dimensions of the sensing element 300. The
drain plug 350 may utilize any variety of physical configurations
(e.g., hex nut) and threading arrangements and may further be
specially manufactured for particular combustion engine/oil
pan/engine environments. The sensing element 300 (as a part of or
independently of the drain plug 350) may also utilize any variety
of O-rings, washers, and/or protective housings in order to
properly protect the sensing element 300 and to otherwise ensure
that housing 310 is properly secured within the drain plug 350.
One of the three chambers of sensing element 300 (e.g., chamber
320) is open. Chamber 320 detects the conductivity of the oil
directly. With regard to chamber 320, conductivity is dominated by
the ionic characteristics of oil additives (oxidation 410) as is
shown in the exemplary oil degradation cycle depicted in FIG. 4. In
the oil degradation cycle of FIG. 4, as additives are depleted the
additives become less polar; as the base oil itself deteriorates,
the base oil becomes more polar.
Returning to FIG. 3, the remaining two chambers (chambers 330 and
340) are covered by a conductive mesh screen (390a and 390b).
Chamber 330 comprises (houses) a matrix of insoluble polymeric
beads (not shown). Chamber 340 comprises a single bead (not shown).
The conductive mesh screen (390a and 390b) may be constructed of
stainless steel cloth.
In a non-polar solution with relatively low conductivity, the beads
in chamber 330 remain separate from one another as is shown in FIG.
5A. It should be noted that in FIG. 5A as well as FIG. 5B--for the
sake of simplified illustration--only a single monolayer of the
charged bead matrix is shown. The fact that only a single monolayer
is illustrated should not be interpreted as otherwise limiting the
present disclosure. As the oil's polarity increases, however, the
conductivity across the matrix increases and the ionic component of
each group of beads relaxes and begins electrically interacting
with an adjacent group in the presence of voltage potential. FIG.
5B illustrates the same whereby the beads form a bridge on the
conductive mesh 390a of the chamber 330. The change in the bead
matrix as illustrated in FIGS. 5A and 5B indicates both additive
depletion and oxidation and is represented graphically by line 420
(additive depletion) in FIG. 4.
The sensing element 300 generates a sensor reading reflective of
oxidation based on a differential measurement of a matrix of
insoluble polymeric beads and the oil being analyzed. Sensing
element 300 further generates a sensor reading reflective of the
presence of soot and similar contaminants based on a differential
measurement of oil inside a filter and the oil being analyzed.
Sensing element 300 further generates a sensor reading reflective
of the presence of fuel, water or similar contaminants based on a
differential measurement of a matrix of insoluble polymeric beads
and the contaminated oil being analyzed. The sensing element 300
may measure oil quality through the use of any one of a number of
different electrical forms including alternating current (AC),
direct current (DC), a combination of AC/DC, in addition to
mechanical forms such as crystal resonance. By utilizing sensor
readings from the three chambers of the sensor array, an accurate
measurement of oxidation, additive depletion, and contamination is
provided, which is more accurate reflection of oil quality
Data readings from open chamber 320 are subtracted from data
readings obtained from the bead matrix in chamber 330. This
subtraction of data may take place in a differential analysis
software module (not shown) in monitoring unit 210 under the
control of a microprocessor (also not shown). Various other
hardware and software elements may be present in monitoring unit
210 to allow for the receipt, processing, analysis, storage, and/or
exchange of data. For example, one embodiment of the present
invention may utilize an application specific integrated circuit
(ASIC) for undertaking the differential analysis otherwise
performed by the aforementioned software module. Through the
subtraction of the open chamber 320 data, effects of additives are
removed from the analysis and only oxidation is measured. In this
regard, no calibration of the system 200 is required and any
differences in various oil formulations are negligible with regard
to a determination of oxidation in the oil under analysis.
This differential measurement technique may be used to determine
the polarity of oil where one chamber measures multiple properties
of the oil and a second chamber measures the same properties with
the exception that it does not measure the polarity of the oil.
Taking a differential measurement between the two chambers allows
for a determination of the polar condition of the oil.
Specifically, if an electrical measurement of the oil is made and a
second electrical measurement is made of an ionic polystyrene
matrix where the electrical signal includes components from both
the oil and the polystyrene matrix then the difference between the
signals shows the polarity of the oil.
Chamber 330 may determine soot contamination in an oil sample
wherein the sensing element 300 has been disposed. Soot
particulates consist primarily of carbon and tend to bind to one
another and to the actual engine. If soot is allowed to aggregate
unfettered, the soot particulates can actually begin to score the
engine bearings. Soot measurement is based on a percentage of the
amount of soot freely available in the oil and is commonly referred
to as the saturated relative contamination. A given amount of free
soot can, in some instances, constitute 1% to 2% contamination for
base oil without additives or greater than 7% for fully formulated
oils.
When a soot dispersant additive begins to fail, the soot begins to
adhere to the surface of the aforementioned polymeric beads and
form a bridge across the chamber 330. When such a bridge occurs,
sensor readings at chamber 330 change dramatically and continue to
increase as more layers of carbon soot accumulate. Conductivity
caused by soot is considerably greater than that due to oil and
additive polarity and is measurable by the present sensing element
300 in addition to capable of being differentiated versus worn
oil.
Soot contamination may be determined using a differential
measurement. By using two chambers--one that measures the
properties of the oil and the other that measures the properties of
the oil after it has passed thru a fine filter that keeps soot or
any other contaminates away from the sensor--soot contamination can
be measured. Specifically, soot that is not chemically capped is
electrically conductive. Taking the differential measurement of two
chambers where one measures all the electrical characteristics of
the oil and the other is precluded from measuring the effect of the
soot (or any other particle) in the oil by a 0.2 micron filter
allows for a determination of soot contamination. This technique is
not limited to an electrical measurement; it could also be used in
an optical measurement.
The third chamber--chamber 340--may detect water contamination in
the oil or fluid under investigation. Water that enters the engine
and boils as a result of engine temperature can cause the engine
oil to turn into a sludge-like substance. This sludge-substance not
only fails to properly lubricate various engine components but can
also rust an engine from the inside-out.
A determination of water contamination in oil may be made using a
differential measurement technique. By immersing two sensor
chambers into the oil--one that measures multiple properties of the
oil and the other measures multiple properties less the property
associated with water contamination--and using a differential
technique, the water contamination may be independently measured.
Specifically, if an electrical measurement of polystyrene matrix is
made where the matrix is relatively insensitive to water
contamination and the signal is compared to a measurement of the
polystyrene matrix that is highly sensitive to water absorption,
the difference between the measurements will allow the water
contamination to be measured.
The measurement may be made electrically or mechanically by looking
at the change in electrical characteristics of the beads or by
looking at the change in physical characteristics of the beads.
Using a highly cross-linked polystyrene matrix will limit both the
mechanical and electrical changes to the bead matrix. Using a
loosely cross-linked polystyrene bead matrix will allow for large
changes in the electrical and mechanical properties of the beads.
The change is proportional to the quantity of water
contamination.
Conventional methodologies report water in oil as a percentage of
total volume. Different blends of oil, however, can consume varying
amounts of water as a result of oil additives binding with water
molecules. As such, an absolute measure of water it not necessarily
helpful or informative. An embodiment of the present invention
reports water content as a percent saturated relative humidity
(SRH) of the oil. An SRH of, for example, 100% where the oil cannot
absorb any more water without its dropping out of solution as
emulsified or free water is same for all oils at a given
temperature.
As noted above, a single polystyrene bead in chamber 340 measures
water contamination corresponding to 2% SRH. The diameter of the
bead is slightly less than the thickness of the sensor
housing/sensor board 310. The bead is extremely hydrophilic and
attracts water, swells and physically contacts the conductive mesh
screen 390b of the chamber 340. The resulting increase in
conductivity is detected as shown in FIGS. 6A and 6B.
FIG. 6A illustrates a single hydrophilic, polystyrene bead in an
environment without `free` water and reflecting relatively low
conductivity. FIG. 6B, however, illustrates the same single
hydrophilic, polystyrene bead in an environment with `free` water
(i.e., water contamination) whereby the bead swells through its
attracting of the `free` water and comes into contact with camber
340's conductive mesh 390b thus reflecting relatively high
conductivity.
The polystyrene beads of the present invention may be impregnated
with charged groups. In one exemplary embodiment, sodium and
sulfite may be utilized as the cation and anion, respectively.
Salts of polyatomic anions such as phosphates and carboxylates may
also be utilized as cation exchange groups. Additionally, anionic
exchange groups may comprise salts of N-alkylated amines. The beads
may be cross linked with 8% divinylbenzene and further comprise a
titer or exchange capacity of 1.7 meq/ml. The beads, further, may
be of 1.180 to 38 .mu.m in diameter; 500 mg of which being
sufficient in the present invention although lesser (and greater)
amounts are possible in the practice of the present invention
(e.g., 20 mg).
The beads utilized in various embodiments of the present invention
may be pre-treated or `prepared` in order to created a polar
environment that allows for more accurate measurement of conditions
in a non-polar environment such as uncontaminated oil
solutions.
Such a process may include washing the beads with 1N sodium
hydroxide for approximately 15 to 30 minutes at room temperature;
the excess sodium hydroxide is washed off in a methanol bath. The
beads are further soaked in methanol to remove any excess water and
then air dried to remove any remaining methanol. The beads are
subsequently soaked in glycerol for approximately 24 hours and then
heated to approximately 140.degree. C. for approximately two hours
to ensure proper penetration of the glycerol. At this point, the
beads are fully swollen.
The beads are then placed in a non-polar fluid (e.g., clean oil)
and again heated to 120.degree. C. to remove excess ethylene glycol
and to further `shrink` the beads to a `clean oil` state. The beads
are then loaded into the various chambers (e.g., 330 and 340) of
the sensing element 300. The beads are typically loaded into the
various chambers (e.g., 330 and 340) of the sensing element 300
under slight to moderate pressure such that the beads are in close
proximity to one another. In an alternative embodiment, the beads
may be further soaked in glycerol to cause slight expansion of the
beads and otherwise obtain bead-to-bead proximity.
Data readings from sensing element 300 are communicated to the
monitoring device 210 of system 200 through any number of wire
tracings 380 on/in the non-conductive housing 310 of element 300.
The conductive pathways of the wire tracings 380 are, in some
embodiments, etched from copper sheets laminated onto the
non-conductive housing 310. In other embodiments, traces may be
added through electroplating. Various other methodologies for
creating the conductive wire tracings 380 on the non-conductive
housing 310 including but not limited to silk screen printing,
photoengraving, and milling. In some embodiments of the present
invention, a series of layers of substrates may make up the
non-conductive housing 310 and a series of blind and/or buried vias
(not shown) may be used instead of (or in addition to) surface
mount methodologies.
These conductive pathways are coupled (e.g., through soldering) to
chambers 310-340 in addition to output connectors 370, which (in
one embodiment of the present invention) extend outward from the
drain plug 350 and toward the various elements on the face of the
non-conductive housing 310 of sensing element 300. Output
connectors 370 serve to couple the wire tracings 380 on the face of
the non-conductive housing 310 to cable connector pins 360 which
extend outward from the drain plug 350 (and away from the
non-conductive housing 310) such that the connector pins 360 may be
connected to sensor signal cable 230 for data exchanges with
monitoring device 210. In this way, data generated at the various
chambers 310-340 may be communicated through wire tracings 380 to
the output connectors 370, which connect to cable connector pins
360.
In some embodiments, output connectors 370 and cable connector pins
360 may be the same uninterrupted element whereby the pins 360
extend through the drain plug housing 350 and toward the
non-conductive housing 310 where one end of the connectors are
soldered to the wire tracings 380. In additional embodiments of the
present invention, that portion of the drain plug 350 most distant
from the oil pan or chamber into which the non-conductive housing
310 is inserted may have a concave design such that the cable
connector pins 360 are partially or entirely housed within the
concave area and protected from damage through exposure to the
elements that might corrode the face of the pins 360 or deform the
shape of the pins 360 (e.g., bending) through impact or other
applied forces.
FIG. 7 illustrates an exemplary interface 700 as may be used with a
monitoring device 210 of an exemplary embodiment of the presently
disclosed oil monitoring system 200. After the aforementioned
differential analysis software module of the monitoring device 210
has undertaken an analysis of the oil data from sensing element
220, the data is displayed in an informative format for the user of
system 200.
For example, overall oil quality may be reflected by one of a
series of light emitting diodes (LEDs) 710 in the monitoring device
210. Various levels of oil quality may be reflected although the
present embodiment reflects levels of <good>, <ok>,
<fair>, and <change>. The latter
setting--<change>--indicates the poor quality of the oil
under analysis and the need for a change of the same.
A similar LED may be utilized to reflect the presence of excess and
unwanted soot in the oil under analysis (LED 720) as well as excess
and unwanted water (LED 730). These indicators, too, may further or
individually reflect the need to replace motor oil before damage to
the engine environment ensues. An overall system status LED 740
indicates that the monitoring device 210 and related equipment is
in overall working order and that `false positives` reflecting
inaccurate oil readings are not being generated.
In another embodiment of the present invention, the interface 700
of the monitoring device 210 may reflect a variety of graphical
outputs. For example, oil quality may be reflected by an LED or
digital image output bar that rises or falls based on the oil
quality. Oil quality may also be reflected by a digital output
reflecting a number indicative of oil quality such that increased
quality accuracy is possible.
Data generated as a result of various oil measurements reflects the
overall quality of the oil. For example, normal oil capacitance and
normal oil conductivity in conjunction with no water absorption is
generally an indicator of overall good oil quality. To the
contrary, high oil capacitance, low oil conductivity in conjunction
with no water absorption may indicate worn oil quality. Low
capacitance and low conductivity of the oil may be reflective of
additive depletion. Soot contamination and water contamination may
be reflected by rapid increases in oil capacitance notwithstanding
normal oil conductivity in conjunction with a lack of water
absorption and the presence of water absorption, respectively.
Various differential measurement outputs (or specific measurements
or ranges of measurement) may be correlated to the aforementioned
interface outputs (i.e., good v. change; graphical bars; numerical
output). In some embodiments, this information may also or,
alternatively, be reflected at the external computing device
250.
In some embodiments of the present invention, a series or array of
oil sensors 220 may be utilized. The collective measurement data is
analyzed by a signal monitoring device 210 or may be collected by
individual monitoring device 210 and subsequently conveyed to the
external computing device 250. Through collection and analysis of
oil quality data from a series or array of oil sensors 220, an even
more accurate oil quality reading may be obtained in that irregular
and/or inaccurate oil readings (e.g., spikes in data) may be
identified and filtered out of the final oil quality analysis. The
collective measurement data may be, for example, batched and
collectively analyzed or serially analyzed as data becomes
available. Parallel analysis of portions of the oil measurement
data may also take place.
While the present invention has been described in connection with a
series of exemplary embodiments, these descriptions are not
intended to limit the scope of the invention to the particular
forms set forth herein. To the contrary, the present descriptions
are intended to cover such alternatives, modifications, and
equivalents as may be included within the spirit and scope of the
invention as defined by the appended claims and otherwise
appreciated by one of ordinary skill in the art.
The aforementioned differential measurement techniques may also be
used for measuring fuel contamination. Using two sensor
chambers--one that is sensitive to fuel contamination and one that
is not sensitive to fuel contamination--and taking the differential
signal between the two allows the for the detection of fuel
contamination in oil. This technique is not limited to the above
examples but can also be used to measure specific additives,
contaminates or differences in other types of base stocks. Further,
the technique is not limited to measuring electrical properties.
The technique may be used to measure a change in size of a
polymeric matrix due to a change in polarity of the oil, change in
chemical composition of the oil due to degradation or change in
size of the matrix due to contamination.
Differential inputs may include beads prepared where one type of
bead can have its ionic group influenced by metals whereas another
group will not be influenced in such a manner. Alternatively, one
group of beads may be prepared such that they react differently
than another group of beads in the presence of fuel. Differential
measurement combinations may take into account one or more of
different bead types, bead cross-linking, bead size, and bead
preparation; the ability to change the physical properties of the
sensor chambers (e.g., filters, electrode size, electrode shape,
and so forth); and electrical excitation possibilities.
Various embodiments of the present invention may be implemented to
analyze a variety of oil types and viscosities. The present
invention may be implemented to analyze fluid substances at a
variety of temperatures. The present invention may further allow
for retrofitting of older oil pans or combustion engines while
further allowing for design-specific configurations. In some
embodiments of the present invention, a sensing element may be
dedicated to a particular oil quality determination and used in
tandem with a series of other sensing elements with respect to
differential measurement of that particular quality or as part of
an array with respect to a determining a variety of qualities
utilizing various differential techniques. The present invention
may be implemented in a variety of different operating environments
including but not limited to gasoline engines, diesel engines,
transmissions, turbines, transformers, gear boxes, vacuum pumps and
other oil-reliant machinery.
Some embodiments of the present invention may employ various means
of metal detection. For example, metal detection may be electrical;
attaching a specific ion to a polystyrene bead may allow for a
specific metal or group of metals to be detected. In one such
example, one chamber of a sensor may contain beads with a hydrogen
ion while the other chamber may contain beads with a barium ion.
The sensor may be placed in an oil solution that contains lead
whereby the lead would displace the hydrogen ion and electrically
`cap` the bead so that it does not change conductivity when
polarity changes. The barium, on the other hand, would not be
affected by the lead and will change conductivity only when the oil
polarity changes. Taking the electrical differential of the signals
generated by the beads in the two chambers will provide an
indication of the lead contamination.
Metal detection may also be visible. For example, in the presence
of copper, a calorimetric change takes place when the hydrogen ion
is replaced by a copper ion. While the copper will replace the
hydrogen ion, the barium ion will not be replaced. Measuring the
differential of the visible spectra of the two chambers may provide
an indication of, in this example, copper contamination in the
oil.
Detection may also occur mechanically or electro-mechanically. The
bead size may change by, for example, 5% when different ions are
attached. Using a mechanical differential measurement methodology
may provide an indication of specific metals. A spring or fulcrum
may be used in some embodiments to show this differential.
While this invention has been described in conjunction with the
specific exemplary embodiments outlined above, many alternatives,
modifications, and variations may be apparent to those skilled in
the art. Accordingly, the exemplary embodiments of the invention as
set forth both are intended to be illustrative and not limiting
except as otherwise set forth in the claims.
* * * * *
References